1. Field of the Invention
The present invention relates to an end burning type gas generator used with, for example, a side thruster or the like of a flight, such as a solid propellant rocket motor or spacecraft.
2. Description of the Related Art
In an end burning type gas generator, a gas generator propellant is filled in, for example, a cylindrical combustor to form the gas generator propellant into a cylindrical shape. The cylindrical shaped gas generator propellant carries out end burning so as to cause the burning to progress in the axial direction, and the combustion gas produced by the combustion is introduced from the combustor into a functional section, such as a nozzle. As such an end burning type gas generator, there has been generally known a rocket motor filled with a solid propellant, which is a gas generator propellant.
However, in the aforesaid end burning type gas generator with the cylindrical gas generator propellant, the burning time is obtained by dividing the axial length of the cylindrical gas generator propellant by a burning rate, so that the axial length of the gas generator propellant increases with increasing burning time. For this reason, the shape of the gas generator propellant is automatically determined according to required burning time or the supply amount of a combustion gas, thus disadvantageously limiting design flexibility. Further, under a design condition that, for example, the full length of a combustor may not be increased while the shell diameter thereof may be increased, there has been a problem in that it is difficult to prolong the burning time or enhance the mass ratio of a gas generator propellant.
To solve the aforesaid problems, the applicant of the present invention has previously invented and filed a shuttle end burning type gas generator disclosed in patent document 1.
As shown in FIG. 1, the shuttle end burning type gas generator disclosed in patent document 1 is a shuttle end burning type gas generator A1 in which a plurality of layers of a gas generator propellant 50 is charged in a combustor 54 through a restrictor 59, and the layers of the gas generator propellant 50 are continuously arranged such that the end burning sequentially progresses from one layer to another. This arrangement implements considerable extension of burning time without the need for increasing the entire length of the combustor 54, leading to considerably increased design flexibility.
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-204947 “Shuttle End Burning Type Gas Generator”
In the shuttle end burning type gas generator described above, the combustor 54 is filled with the end burning type gas generator propellant 50, which has the side surface thereof burning-restricted by a restrictor 59 and which is annularly arranged as if the gas generator propellant 50 is folded from inside to the outside. Thus, the gas generator propellant 50 is formed in two layers in the illustrated cross-section, and has an exposed end surface 51 at one end of the combustor 54 at right in the figure, while the inner layer and the outer layer continue at the other end.
However, in the gas generator disclosed in patent document 1, the turning portion burns more slowly along the outer periphery thereof than along the inner peripheral thereof, resulting in different burning areas before and after the turning portion. For this reason, eliminating the difference in burning area by means of the shape of a propellant inevitably involves a complicated shape. More specifically, the restrictor 59 of the gas generator is three-dimensionally turned from inside to outside, leading to a complicated shape of the propellant. This has been presenting a problem in that the mass ratio of a gas generator propellant is low and a complicated process is required for charging the gas generator propellant.